This invention relates generally to folding grandstands or bleachers of the type which comprise hinged supporting frame sections carrying seats and footboards and adapted to assume a sloping or inclined position when opened for use or occupancy, but capable of being folded together to occupy a minimum of space at the playing field when collapsed.
Grandstands of this general type are typically comprised of two or three supporting frame sections horizontally hinged together at their adjacent ends by the provision of hinge assemblies between sections to facilitate a folding together of the sections in a fanfold manner.
Prior grandstands of this general type are usually structured in essentially the same manner, i.e., each supporting frame has a deck plate spanning across and supported on longitudinal steel beams. The beams are supported on rolling dolly assemblies when the grandstand is in the stored or folded position and while the grandstand is in transition between the folded and extended positions. The dolly assemblies roll along tracks or troughs that are supported on or in the sport playing field surface below. When the grandstand is in the extended position, ready for use or occupancy, each of the longitudinal beams are supported by the rolling dolly assemblies and each of the longitudinal beams are supported by additional foldable frame assemblies as required to properly support the additional live loads.
Because the underlying dolly assemblies and frame supports are hingedly connected to each of the longitudinal beams of the supporting frame sections, ground tracks are required for each of the dolly assemblies and support frames. These tracks must be installed in the ground for rolling engagement by the dollies prior to extending the grandstand from its collapsed position, and the tracks must be removed from the field after the grandstand is collapsed back to its stored position.
Thus, the number of tracks required for each of the longitudinal beams of the grandstand creates a time and labor intensive operation for assembling and removing tracks each time the grandstand is extended and folded. Also, the storage and handling of a large number of tracks, each comprising several sections, is costly and cumbersome.
Also, each of the many footings on which the tracks are supported are typically covered by continuous grass sod pans after the tracks are removed, such that it becomes costly and labor intensive to remove and replace the sod. And, the sod overlying the many footings can create hazards for the players on the field.